The evolution of the unstable cancer genome.

Cancer next-generation sequencing and genomics studies published over the last five years have provided unprecedented insights into the forces shaping cancer genome evolution. In particular, these studies have revealed a high level of heterogeneity not only between different tumours, but also within individual tumours; the 'cancer genome' may evolve along several independent trajectories within a single tumour. There is an increasing appreciation of the importance of intratumour genetic heterogeneity in determining disease progression and clinical outcome in cancer medicine, and thus an increasing awareness of the need to understand the processes that both generate genetic diversity and shape genome evolution in human tumours.